Air conditioning system



Feb. 24, 194-2. MILLERETAL 2,274,153

- 1 AIR counnxoume SYSTEM Filed July 16, 1937 s Sheeis-Sheet 1 Feb. 24, 1942. L. B. MILLER ETAL 2,274,153

" AIR CONDITIONING- SYSTEM Filed July 16, 1937 s Sheets-Sheet 2 a fl/ SEQUENCE CONTROLS To STARTlNG AND \GNIT'ION CONTROLS Inventors TO START! N 1 AND IGNTION I CONTROLS Feb. 24, 1942.

L. B. MILL-ER ETAL AIR counmroume SYSTEM Filed July 16, 1957 Z5 Sheets-Sheet 3 I [120mg 5/ ,Jnve-rztors Leo B. M1 2261 water and for reheat. object of our invention to automatically utilize Patented Feb. 24, 1942 UNITED STATES PATENT OFFICE f 1.274453 v AIR CONDITIONING SYSTEM Leo B. Miller, Hartsdale, N. 'Y.-,' William L.

McGrath, St. Paul, Minn., and John E. Haines,

Chicago, Ill., assignors to Minneapolis-Honey well "Regulator Company, Minneapolis, Minn, a corporation of Delaware Application July 16, 1937, Serial No. 154,025

'23 Claims. (01. 62-6) This invention relates to air conditioning systems and is more particularly concernedrwith air conditioning systems for summer cooling of the type utilizing a compression refrigeration system wherein the compressor is-w driven by means of an internal combustion engine. 1

. .One object of our invention is to provide an air conditioning. system adapted to economically maintain proper temperature conditions within a space, such system being. driven by an internal combustion engine and being provided with a reheater for reheating the air after being cooled and dehumidified, such reheater being suppliedwith waste heat from the engine.

More specifically, it is an object of our invention to provide a system of the type mentioned, with an automatic, control system for varying the output of the engine and the opera- I tion of the reheater in accordance with changes in temperature and humidity conditions in a manner to maintain proper psychrometric conditions within the conditioned space. A further object of 'our invention is the pro-v passed in heat exchange relationship with a heat exchange fluid which is circulated to absorb heat from the engine cylinders and the exhaust gases. 7

A still further object is to provide an arrangement for storing the waste heat ejected by'the engine as by storing a-body of heated fluid which is heated with such waste heat, this stored heat being available for satisfying various demands for heat such as for'supplyin-g domestic hot More specifically, it .is an sequentially controlled in such manner that the reheater is not placed. into operation until the lay-pass damper is wide open, thereby avoiding addition of heat to theair being conditioned at all timesexcept when such addition of heat is necessary in order to secure the required of dehumidiflcation.

Another object is the provision of an air conditioning system having a refrigeration system with a control arrangement for automatically.

for cooling and dehumidifying and having also a reheating means such system'being provided controlling the operation of the refrigeration system'and the reheater, such control arrangement acting to control the operation of the refrigeration system in accordance with thesuc- .tion or low side pressure-and to control the opverationof the reheater in accordance with temperature and/or humidity conditions of the space being conditioned in a manner to maintain such conditions within predetermined ranges of values.

Other objects will become apparent from the following description and the appended claims.

For a full disclosure of our invention; reference is made to the following detailed descriptionand to the accompanying drawings, in which-'- Figure 1 illustrates diagrammatically an air conditioning system embodying one form of our.-

-invention,

5 Figure 1a shows the same system as Figure 1 i but omits thewiring diagram,

the stored heating fluid for reheat as by passing said fluid through the reheater when reheat is required.

Another object of our invention is to'provide a control arrangementior an internal combusgtion driven air conditioning system which acts automatically to control the relative humidity within the conditioned space by varying the output of the internal combustion engine ina'ccordance with changes in relative humidity," such cooling and dehumidifying device of the type having a damper controlled by-pass therearound and a reheater, the by-pass and reheater being Figure 2 illustrates diagrammatically another form which our invention may take, and

Figure 2a is a simplifiedshowing of Figure 2, Y -omitting the wiring diagram.

Referring now to Figure 1, reference character l indicates an air conditioning chamber having a return air inlet duct-2 which leads from a space to beconditioned 3. Conditioning chamher I is also provided with a fresh air inlet duct 4, this duct being provided with suitable dampers '5 for controlling the admittance of fresh air.

To the discharge end of conditioning chamber I is connected a fan' 6, the disc'hargeof this fan being connected to a discharge duct 1 which leads to the conditioned space 3. The fan 6 is provided with suitable driving means such as an electric motor 8. Located within the conditioning chamber l is a cooling coil 9, a bafile Ill being provided for forming a by-pass passage ll around said cooling coil. For controlling the amount across coil 9 at all times.

actuated by a rod I4, which is connected to the actuating arm of proportioning motor I5, the arrangement being such that when the face dampers are moved towards closed position the by-pass dampers are simultaneously moved towards open position and vice versa. The face dampers [2, it will be understood, are never entirely closed by motor l5 and permit air to flow Also located in the conditioning chamber l is a reheater l6.

For supplying liquid refrigerant to the cooling coil 9 and for withdrawing evaporated refrigerant therefrom, a compression type of condensing unit'isprovided which comprises a compressor l1 and a condenser l8. The discharge of the compressor I1 is connected by means of conduit H! to the refrigerant inlet of condenser l8. To the refrigerant outlet of the condenser is connected a conduit which may lead through a suitable receiver (not shown), to the inlet of an expansion valve 2|. valve may be of any desired type and is herein illustrated as being of the thermostatic type comprising a temperature control bulb connected to the outlet of the cooling coil 9. Said cooling coil outlet is connected by a conduit 22 to the suction side of the compressor l1. Com,- pression refrigeration systems of this type are well known in the art and hence a detailed description of the operation of such a system is unnecessary here. However, it may be stated that operation of the compressor II causes chilling of the cooling coil 9, and that the amount of cooling done by cooling coil 9 varies with the compressor speed.

For driving the compressor I) an internal combustion engine 25 is provided, this engine having the usual inlet manifold 26, exhaust manifold 21, starting motor 28, generator 29, and a flywheel which has located therein a suitable clutching mechanism. In starting an engine of this type it is desirable to disconnect it from its load and'for this purpose an automatic clutching mechanism is provided which comprises a bell crank lever 3| for actuating the clutch release collar 32, thebell crank lever being connected to a pneumatic motor 33. The pneumatic motor 33 comprises a piston 34 located in a suitable cylinder, this piston being urged outwardly by a spring 35, this causing disengagement of the clutching mechanism. The interior of the cylinder is connected by a conduit 36 to the intake manifold 26. By this arrangement, when the engine 25 is started the resulting vacuum in the intake manifold 'will cause movement of the piston 34 against the action-of the spring to engage the clutching mechanism, thus causing the engine 25 to rotate the drive shaft .31. The

drive shaft 31 carries a pulley 38 which drives the belts 39 which in turn rotate the pulley 46 mounted on the compressor shaft. and in this manner the compressor I1 is driven by the internal combustion engine 25. Also mounted upon the shaft 3'! is a second pulley 4|, this pulley being provided for driving the pumps 42 and 43 through the medium of belts 44.

For controlling the speed of the engine 25 a throttle valve45 is provided which controls the flow of a combustible mixture of fuel and air into the engine cylinders. It will be understood that a suitable fuel mixing device (not shown) is employed for mixing the fuel and air prior to passage to the throttle valve 45. The throttle valve 45 is controlled by means of a proportion- This expansion ing motor generally indicated at as, this motor comprising an operating shaft 41 upon which is mounted an actuating lever 48 which is connected to the throttle valve by suitable linkage. The operating shaft 41 is rotated through a gear train 49 by means of a pair of induction motors comprising armatures 50 and 5| and cooperating field coils 52 and 53. It will be understood that energization of the field coil 52 will cause rotation of the shaft 41 in one direction and energization of the field coil 53 will cause rotation of said shaft in the opposite direction, the shaft 41 remaining stationary when both field coils are deenergized. No novelty is claimed for the proportioning motor illustrated herein, this type of proportioning motor being shown in the patent to D. G. Taylor No. 2,028,110, and being controlled by a relay of the electrically balancing type. Mounted on the shaft 41 is an arm 55 which cooperates with a resistance 56 to form a balancing potentiometer. Also mounted on the shaft 4"! is an insulated actuating member 51 for actuating the limit switches 59 and 59, these limit switches being provided for deenergizing the field coils 52 and 53 when the shaft 41 is rotated to one limit or the other of its travel.

For controlling the energization of the field coils 52 and 53, a balancing type of relay is provided, this relay being generally indicated as 60 and comprises a pair of connected relay coils 6| and 62 for controlling through a suitable armature, a switch arm 63 which cooperates with a pair of contacts 64 and 65. When the relay coils 6| and 62 are equally energized, the armature will assume a midposition in which the switch arm 63 is disengaged from both contact 64 and contact 65. If, however, the relay coil- 62 is energized more highly than relay coil 6| the switch arm 63- will be brought into engagement with the contact 65. Conversely, if relay coil 6| is energized more highly than relay coil 62 the switch arm 63 will be caused to engage the contact 64.

In accordance with our invention the speed of the engine is controlled in accordance with the relative humidity of the space being conditioned, and for this purpose the humidity controller 66 is provided for controlling the relative energizations of the relay coils 6| and 62. The humidity controller 66 comprises a humidity responsive device 61 for controlling a potentiometer 68, this potentiometer comprising a slider 69 cooperating with a resistance coil 10. The humidity responsive device comprises upper and lower clamping members for securing a plurality of hairs or other moisture responsive'strands, the lower clamping member being connected to a suitable fixed support and the upper clamping member being connected so as to actuate the slider 69. A spring H is provided for urging movement of the slider 69 against the action of the humidity responsive device. Upon an increase in humidity the strands of the moisture responsive device 61 will increase in length, this permitting rotation of the slider 69 in a counterclockwise direction under the action of spring II. A decrease in humidity, however, will cause the moisture responsive strands to decrease in length, this causing rotation of slider 69 in a clockwise direction against the action of spring H.

For supplementing the control of the balancing relay 6!) by the humidity controller 66, a temperature controller 15 is provided, this temperature controller comprising a bellows 16 which is secured to a fixed support at its lower end and which is arranged to operate a pivoted mercury the return air duct 2.

switch carrier .11 which carries a mercury switch 18. The bellows 16 is connected by a capillary tube 19 to a control'bulb 69 which is located in of the return 'air is below 82 the bellows '|6 will be contracted sufficiently to cause the switch 18 to be tilted. so that its right-hand contacts are closed. When, however, the temperature of i the return air exceeds 82 F., the bellows 16 will expand to cause breaking of the right-hand con tacts of mercury switch 18 and making of the left-hand contacts thereof. U

Reference character 8| indicates a step-down transformer connected to any suitable source of power, the secondary 82 of said transformer be-. ing connected across the serially connected relay coils 6| and 62 by means of wires 83, 84, 85 and 66. Also connected across the serially connected relay coils 6| and 62 are the resistance 56 of the balancing potentiometerand the control resist ance 10 of the humidity controller, the resistance 56 being connected to said relay coils by means of wires 81 and 88 and the protective resistances 89 and 90. The control resistance 10 is connected to said relay coils. by wires 9| and 92 through the protective resistances 89 an 90. The slider 55 of the balancing potentiom ter is connected to the junctionof the relay coils 6| and 62 by meansof wires 93 and 94. Thejunction of relay coils 6| and 62 is also connected to the common terminals of the mercury switch 18 by means of wires 94 and 95. The right-hand terminal of mercury switch"!!! is connected by a wire 96 to the slider 69 of the humidity controller. It should thus be seen that when the mercury switch 18 is tilted to the position shown, the slider 69 of the humidity controller is connected to the junction of relaycoils 6| and 62. The left-hand The bellows l6, tube 19- and bulb 86 contain a suitable volatile fluid 59, wire99, field coil 53, wire I 00 and wire 86 to theother side of secondary 82. This will result in rotation of the shaft 41 in a direction to cause opening of the throttle yalve 45 and to cause counter-clockwiserotation of thslider of the balancing potentiometer. This movement of the slider 55 will have the'efiect of decreasing the portion of balancing resistance 56 which is in parallel with the relay coil 6| and increasing the portion of said resistance which is in parallel with the relay coil 62. This action therefore tends to balance out the initial -'unbalancing efiect on the relay 60 caused by the humidity controller 66. When the movement of slider 55 is such that it's balancing action balances out the initial unbalancing action of the humidity controller, the relay coils 6| and 62 will become equally energized thereby causing the switch arm63 to disengage contact 64, thus, stopping the motor in this new position. It should thus be seen that the angular travel of the shaft 41 will be proportional to the travel of the slider 69- of the humidity controller across the control resistance 1|]. It should be apparent that upon decrease in relative humidity the slider 69'will travel in the opposite direction across the control resistance 16, this unbalancingthe relay 66 in the opposite direction, thus causing the switch arm 63 to engage the contact for energizing the field coil 52' which will result in the shaft 41 being rotated ina direction to close the throttle valve 45. It should also be apparent that this rotation of the shaft 41 will cause the balancing potentiometer to stopvthe motor in a position corresponding to the position of the slider69 on the control revariations in relative humidity within the con ditioned space, thethrottle valve being opened to contact of the mercury switch 18 is connected by means of wire 91 to the left-hand end of the control resistance 16.

From the foregoing wiring connections, it will be apparent that the slider 69 of the humidity controller 66 will place the portion of the control resistance 16 which lies to the left of said slider.

is in parallel with the relay coil 6| will be increased. This will result in an increase in cur-. rent flow through the relay coil 6| and a decrease in current flow through the relay coil 62 which causes engagement of switch arm 63 with contact 64. Engagement of switch arm 63 with contact 64 will energize the field coil 53 by a circuit as follows: Transformer secondary 82,. wire 83,

switch arm 63, contact 64, wire 98, limit switch noted that the slider 69 of the humidity controller is engaging the extreme right-hand end .of the control resistance 10 thus indicating that within the conditioned space exceed 82 E, the

temperature controller 15 will cause'the mercury switch 18 to be tiltedin a counter-clockwise direction to break the right-hand contacts and to make the left-hand contacts. The breaking. of the right-hand contacts will disconnect the slider 69 from the junction of the relay coils 6| and 62 and thus the position of the slider69 on the resistance I0 will no longer have anyeifect upon the anergization of said relay-coils. The making of the left-hand contacts of mercury switch |8 will cause the relay coil 62t0 be substantially leftshort-circuitedby the following. circuit: hand end of relay coil 62, wire 94, wire 95, mercury switch 18, wire 91, wire 92, and protective resistance to the ri ht-hand end of relay coil 62. This will cause the relay coil 6| to be considerably more highly energized than relay coil 62 thus causing switch arm 63 to engage the con tact 64 which in turn will result in rotation of the shaft 41 in a direction to open the throttle ity conditions within the conditioned space. Thus I as the relative humidity increases, the compressor speed will be increased, this resulting in a lowering of coil temperature. This lowering in the cooling coil temperature will result in an increase of the dehumidifying action of saidcoil. Similarly, uponfalling relative humidity the compressor speed will be reduced, this causing the cooling coil temperature to increase thereby decreasing the dehumidifying action of said cooling coil. By controlling the compressor speed in accordance with the relative humidity within the conditioned space, this condition is maintained within predetermined limits. If at any time the temperature within the conditioned space becomes excessive, it will be apparent that the temperature controller 15 will cause operation of the compressor at maximum output for reducing such excessive temperature condition.

Our invention also contemplates the provision of automatic stopping and starting mechanism for the internal combustion. engine 25. This mechanism will now be described. Actuated by the proportioning motor shaft 41 is a switching member IOI which is arranged to actuate the auxiliary switch formed of mercury switch I02 which is mounted upon carrier I03. The switching member IOI is so adjusted upon the shaft 41 that when the throttle valve is closed to such a point as to indicate the minimum desired operation of the engine 25, said switching member will cause tilting of mercury switch I02 to open position. When, however, th throttle valve 45 is opened sufliciently to cause efficient and satisfactory operation of the engine 25, the switching member IOI will permit tilting of switch I02 to closed position under the action of tension spring I03a.

Reference character I04 indicates a storage battery, one terminal of which is connected by means of wire I05 to the mercury switch I02, and

. the other terminal of which is connected by wire I06 to a suitable ground connection. The other terminal of mercury switch I02 is connected by wires I01 and I08 to one terminal of an ignition coil I09 for the engine 25, the other terminal of said ignition coil being grounded. By the arrangement just described, the ignition coil I09 will be energized whenever the throttle valve 45 is opened sufiiciently to permit closing of the mercury switch I02. The mercury switch I02 is also connected by wire I I0 to the starting motor relay I I I. Thus simultaneously with the energizing of the ignition coil I09 the starting motor relay will be caused to energize the starting motor 28 for cranking the engine. This starting motor relay is arranged to automatically cause deenergization of the starting motor 28 when the engine starts, and is also arranged to prevent energization ofsaid starting motor so long as the engine is in operation. For the constructional details of the starting motor relay III and the principles of operation thereof, reference is made to Patent No. 1,773,913 issued on August 26, 1930, to L, K. Loehr et al., Reference character I I2 indicates an automatic cut-out for the generator 29 which disconnects said generator from the storage battery whenever the engine is out of operation.

' From the foregoing it should be seen'that when the throttle valve is automatically opened t such an extent as to permit satisfactoryoperation of the engine, the engine will be automaticallystarted by the closing of mercury switch I02. It should also be apparent that when the'throttle valve 45 is closed to such an extent that the e."\- gine no longer operates satisfactorily and etc-- ciently, the switching member IOI will cause opening of mercury switch I02 which will deenergize the ignition coil I09 for theengine, thus placing said engine out of operation.

Our invention contemplates not only controlling the compressor speed in accordance with relative humidity, but also contemplates control of the temperature of the conditioned space by controlling the amount of air passed over the cooling coil 9, and also by reheating the air when necessary. Our invention further contemplates the recovering of the waste heat given oil by the internal combustion engine and the condenser, and the utilizing of this waste heat for reheating when necessary, and also for other uses such as providing a supply of domestic water. This heat recovery system will now be described. Reference character II5 indicates a suitable form of cooler which may take the form of an evaporative cooler or a spray pond. Connected to the cooler I I5 is a conduit I I6 for withdrawing cold water from said cooler, this conduit being connected to the intake of circulating pump 43, the discharge of said pump being connected by a conduit I I! to the cooling water inlet of the condenser I8. The cooling water outlet of the condenser I8 is connected by a conduit I I8 to the inlet of the cooling water jacket of the engine 25, the outlet of said jacket being connected by a conduit II9 to the coil I20 located within the exhaust gas heat exchanger I2I. This heat exchanger is connected by pipe I22 to the exhaust manifold 21 and hence the exhaust gases for the engine pass in contact with the coil I20 located within the heat exchanger. The outlet of the cooling coil I 2| is connected by a conduit I23 to the inlet'of coil I24 which is located within a storage tank I25. The

outlet of the heat exchange coil I24 is connected water is first passed through the condenser for cooling the condenser to eifect liquification of the' gaseous refrigerant, this cooling water thereby becoming heated by the heat withdrawn from the refrigerant. This heat-ed water then passes into the water jacket of the engine which is considerably warmer than the condenser and is thereby further raised in temperature. Finally this water passes through the exhaust gas heat exchanger wherein it comes into heat exchange relationship with the extremely hot exhaust gases, and is thereby raised to a high degree of temperature, this highly heated water then flowing through the heat exchange coil I24 thereby giving up the heat which it has received to the hot water or other fluid located in the storage tank I25,

The water or other fluid in the storage tank I25 may obviously be used for any desired purpose, such as providing a supply of domestic hot water. This heated fluid is also adaptable for .shaft I45 will assume a corresponding angular heater I6 is connected'by'a' conduit I28 to the intake of the circulating pump. 42, the discharge of this pump being connected by conduit I29 to the inlet of the storage tank I25, a throttling valve I30 being interposed in said conduit.

In accordance with one form of our invention. 1 we provide a temperature controlled system for maintaining the temperature within the condi-" tioned space within predetermined limits, this being accomplished'by controlling the flow of air .overthe cooling coil, and'also by providing reheat. In accordance with our invention, upon falling temperature we first gradually reduce the air flow across the cooling coil 9 and increase 7 the air flow through the by-pass, and if the temperature still continues to fall after the bypass is wide open the reheater is placed into operation. The control mechanism for achiev ing this result will now be described.

Reference character I indicates generally a temperature controller, this temperature controller comprising a bellows l36 which is fixedly secured at its lower end and which is connected by means of a capillary tube I3I to a control bulb I38 located in the return air duct 2. The bellows I36 is arranged to cooperate with a bell crank lever I39 having an actuating arm I40 and a control arm I4I, said control arm I4I being arranged to contact a control resistance I42 to form a control potentiometer. A spring I43 is connected to the actuating arm I40 and urges -this arm downwardly against the bellows I36. The bellows I36, tube I31, and bulb I38 are filled with a suitable volatile fluid wherefore the pressures within bellows I36 will vary with the temperature to which the controlbulb I38 is subjected. When the return air temperature increases, the pressure of the volatile fluid will increase, this causing expansion of the bellows I36 and movement of the control arm' I to'the left across resistance I42 against the action of spring I43. Upon falling return ,air temperature, the pressure of the volatile fill decreases, this permitting the spring I43 to cause travel of control arm I4I across'the control resistance I42 in the oppositedirection.

The return air controller I35 is connected to the proportioning motor I44, this motor being of the type shown and described in the Taylor Patent 2,028,110. As should now be apparent, the shaft I of the proportioning motor I44 will assume angular positions corresponding to the position of the control arm I4I on the control resistance I42. In other words, for each value of return air temperature the operating position. Mounted upon the operating shaft I45 are sliders I46 and I4! which cooperate with control resistances I48 and I49 respectively. The.contr0l resistance I48 and slider I46 comprise a control potentiometer for controlling the proportioning motor I5 which operates the face and by-pass dampers I2 and I3. The resistance I49 and the slider I4'l comprise a control potentiometer for controlling the proportioning motor I50 which operates the reheat control valve I30. It will be noted that the control resistances I48 and I49 are arranged so as to occupy but a'portion of the range of rotation of their respective sliders, the resistance I48 being arranged to the left of the center of movement of the sliders 7 I46 and I41, and the resistance I49 being arranged to the right of such center of rotation. By this'a'rrangement, it will be seen that as the shaft I45rotates from its extremecounter-clockwise limit of rotation, the slider- I46 will travel across the'resistance I48 while the slider I41 engages contact segment I49a which is attached I to the extreme left-hand end of resistance I49.

face damper I2 is closed. The proportioningmotor I50 which controls the valve I30 is connected to the resistance I49.and the slider I41 in such manner that as the slider M1 is rotated in a clockwise direction the valve I30 is gradually opened. With the operating shaft I45'in the position shown, theslider M6 is engaging the midportion of the resistance I48 and consequently the proportioning motor I5 has assumed a position in which the face and by-pass dampers are in midposition. Also the slider I4'I is contacting the contact segment therefore the proportioning-motor I50 has assumed the position in which the reheat valve I30 is closed. If now should the return air temperature decrease, the temperature controller I35- will cause'the proportioning motor I44 to rotate the shaft I45 in a clockwise direction, this causing movement of the slider I46 across the resistance I48 to the right, thereby causing the proportioning motor I5 to open further the by-pass damper I3 and-to close further the face damper I2. At this time, the valve I30 ,will remain closed due to the slider I4I nothaving yet engaged the end of control resistance,l49. Upon -a further fall in temperature, the by-pass dampersI3 will be further opened and the face dampers I2 will be further closed, and when the fall intemperature is such that the slider I46 engages the extreme right-hand end of the resistance I48, the by-pass dampers I3 will be completely opened. Upon continued fall in temperature the'slider' I46 will begin sliding across the resistance I49, this causing the proportioning motor I50 to open gradually the valve I30. By this arrangement it should be apparent that so longas the space temperature is above a predetermined value the reheater valve I30 will remain closed and the control of the temperature will be eifected solelyv by adjusting the face and by-pass dampers. When, however, the by-pass dampers are moved to completely open position and the temperature continues to fall, the reheater control valve I30 will begin opening, thereby providing a supply of heated fluid to the reheater, the quantity of heated fluid supplied being progressively increased as the temperature continues to fall.

From the foregoing description it should be apparent that our invention provides automatic control of the internal combustion engine in accordance with the relative humidity of the space to be conditioned, this system acting automatically to start the engine whenever the relative humidity rises to such a value that the 'cooling load would be sufficient to require the engine to operate at a satisfactory operating speed. It

H911 and humidity increases, the speed of the engine will be increased, this causing thetemperature of the cooling coil to be decreased thereby increasing the dehumidifying effect of the coil to prevent further increase in such relative humidity. Upon a decrease in relative humidity, the speed of the engine will be decreased, thus decreasing the temperature of the cooling coil and thereby decreasing the dehumidifying action. The compressor speed is therefore controlled in a manner to maintain proper relative humidity conditions within the space so long as the temperature within the space is not excessive.

Simultaneously with the control of the coolin coil temperature by the relative humidity conditions, the flow of air over the cooling coil is controlled in order to maintain the temperature conditions within the space at the desired value. Thus as the temperature within the space increases, the air flow across the cooling coil is increased to increase the cooling action of said cooling coil. It will be apparent that this increase in air flow will result in increasing the temperature of the cooling coil, thereby decreasing the dehumidifying effect of such coil. This will result in the relative humidity within the space eventually increasing and the humidity controller 66 in response will cause the speed of the engine to be increased to carry this increase in cooling load due to the temperature increase within the space. It should also be apparent that upon a decrease in temperature within the space the temperature controller I35 will act to cause closing of the face dampers I2 and opening of the by-pass dampers I3, this decreasing the fiow of air across the cooling coil 9 thereby decreasing the cooling effect of said coil upon the air, thus tending to prevent further fall in space temperature.

In the event that the cooling load is light but the relative humidity within the space is excessive, the cooling coil may be lowered in temperature for dehumidification purposes, to such an extent that the space is overcooled even though the by-pass dampers I3 are wide open. If such a condition should occur, the temperature controller I35 will cause opening of the reheat control valve I30 thus providing a supply of heat for heating the air after it has been cooled for dehumidifying purposes. By the sequential control of the face and by-pass dampers and of the reheater, reheat is first provided by by-passing air around the cooling coil and when such arrangement is incapable. of preventing thetemperature from falling, the reheater is placed into operation. This sequential control thus provides reheat without actually adding heat to the air being conditioned so long as possible, and adds heat to the air being conditioned only when the operation of the system for dehumidification results in cooling of the air to such an extent that reheat is required. Then and only then is reheat supplied.

From the foregoing description, it should also be apparent that whenever the temperature.

within the conditioned space becomes excessive, the control of the speed of the internal combustion engine is taken away from the humidity controller and the engine isoperated even though the humidity may be relatively low.-- The system which we have disclosed, therefore, provides a very flexible and simple arrangement for maintaining proper conditions within the conditioned space regardless of the type of conditioning load.

Figure 2 Referring now to Fig. 2, we have shown in this figure a modified form of control system. The internal combustion engine controls, the refrigeration system and the conditioning chamber are substantially the same as in Fig. 1 and are indicated by the same reference characters. In this embodiment, however, the compressor speed is not varied in accordance with changes in relative humidity as in Fig. 1, but is varied in a manner to maintain the air leaving the cooling coil at a constant dew-point temperature. For this purpose the compressor is controlled in accordance with the suction pressure of the refrigeration system by means of the suction pressure controller 200, this controller being arranged to control the proportioning motor 46 which in turn adjusts the throttle valve 45. Also, in Fig. 2, instead of controlling the dampers I2 and I3 in accordance with return air temperature alone, the control of said dampers is effected in accordance with the effective temperature within the conditioned space, the value of effective temperature being raised or lowered in accordance with variations in outside temperature.

Due to the use of dew-point control, it is desirable to pass air over the cooling coil at all times. For this purpose, the face dampers I2 may be arranged so that they do not completely close, thereby insuring that at least a predetermined amount of air will flow across said coil at all times.

Referring now to the suction pressure con-.

troller 200, this controller comprises a bellows 20I, the interior of which is connected to the suc tion line 22 of the refrigeration system by means of a conduit 202. The bellows 20I is arranged to actuate a bell-crank lever comprising an actuating arm 203 and a control arm 204, said control arm cooperating with a control resistance 205 to form a control potentiometer for controlling the proportioning motor 46. The actuating arm 203 is connected to a spring 206 which urges said arm downwardly against the bellows 20 I. Upon an increase in suction pressure the bellows 20I will expand, this causing counter-clockwise rotation of actuating arm 203 and movement of control arm 204 to the left across control resistance 205, this causing the proportioningmotor 46 to rotate its operating arm in a direction to open further the throttle valve 45.' Upon a decrease in suction pressure the bellows 20I will be contracted by the action of spring 203, this causing travel of the' control arm 204 to the right across resistance 205, which in turn results in movement of the proportioning motor 46 in a direction to move the throttle valve towards closed position. The suction pressure controller 200 therefore acts to increase the speed of the engine upon an increase in suction pressure and to decrease the speed of the engine upon a decrease in suction pressure in a manner to maintain the suction pressure within predetermined limits.

The proportioning motor I5 which actuates the face and by-pass dampers I2 and I3 comprises an operating shaft 208 upon which is mounted a lever 209 which in turn is connected to the operating member I4 forthe dampers. The operating shaft 208 is rotated through a gear train 2I0 by means of a pair of induction motors comprising armatures 2H and 2I2 and corresponding field coils 2I3 and 2I4. It will be understood that the motor formed of armature 2H and field coil 2I3 acts to drive the operating shaft 208 in one divaries in accordance with outside temperature.

rection and that the motor formed of armature 2l2 and field coil 2 acts to drive said operating shaft in the opposite direction.

The energization of field coils 2I3 ;v and 214 is controlled by means of the balancing relay 215,

this'relay comprising connected relay coils 216 through a suitable armatiire a switch arm 218 which cooperates with a pair of contacts 2 l9 and 220. It will be understood that when relay coil H1 is energized more highly than relay coil 2 l6, the switch arm 2I8 will engage the contact 220.

Conversely, when therelay coil 2l6 is energized mounted upon the operating shaft 298 of the proportioning motor, and a' balancing resistance 226.

Referring to the return air temperature controller 2 2 l,;this controller comprises a bellows 221 connected by a capillary tube 228 to a control bulb 229 located in the return air .duct. It will be imderstood that if desired this controller may be located within the conditioned space instead of in the return air duct. The bellows, bulb, and tube are filled with .a suitable volatile fluid wherefore thev pressures within the bellows vary in accordance with the return air temperature. The

bellows 221 is fixed at its lower end and is. ar-

ranged to actuate a lever 239 which inturnactuates a control arm 231 and a corrector arm 232,

the control arm 23l engaging a control resistance- 233 and the corrector arm 232 engaging a correctorresistance 234. 'It willbe understood that as the space temperature decreases, the bellows will contract under the action of the spring shown, this causing counter-clockwise rotation of the control arms 234 and 232 across their respective resistances, and that upon an increase in temperature, the bellows 221 will expand thus Bellows 245 cooperates with a bell crank lever 2 having an actuating arm 248 and a control arm and 2H. The relay coils 2l6 and 2H control 249, said control arm cooperating with the control resistance 259to form a control potentiome ter. Ithwillbe apparent that upon an increase in outside temperature, the bellows245 will expand against the action of the spring shown, thus causing movement of the control arm 249 to the right I across the control resistance 250. Conversely,

upon a decrease in temperature the bellows 245 will contract and the control arm 249 will be moved in the opposite direction under the action causing movement of said control arms in the opposite direction.

The humidity controller 222 comprises a humidity responsive device including a plurality of strands 235 of hair or other moisture responsive material, these strands being connected at their upper ends to a clamping member 236 and at their lower ends to a clamping member 231, this clampirfg member being secured to a suitable stationary element. The upper clampingmember 236, however, is connected to the actuating arm 238 of a bell crank lever including a control arm 239. A

tension spring 240 is also connected to the actuating arm 23,8 and serves to maintain the strands 235 taut. Upon a decrease in relative humidity, the strands 235 will decrease in length, this ,causing downward movement of the actuating arm 238 against the action of the spring 240 thus rotating tacts 219 and 220. For.this position of th mo-':

tube 246, to a control bulb 241 which may be 10- cated in the fresh air duct. and bellows are filled with a suitable volatile fluid This bulb, tube whereforethe pressure within the bellows 245 of the spring.

transformer having a high voltage primary 252 and a low voltage secondary 253. The upper end of secondary 253 is connected to awire 254, this wire in turn being connected to the' left end of resistance 2 by wire 255, to the left end of resistance 233 by wire 256, to the left end of the balancing resistance 226 by the wire 251, and to the right-hand end of resistance 25!] by wire 258. To the lower end of the'transformer secondary 253 is connected a wire 259, this wire being connected to the other ends of the four resistances just mentioned. The left-hand end of the relay coil 2l6 is connected to the wire 254 by means of wire 260 and is therefore connected to the upper end of the transformer secondary 253. The right-hand end of the relay coil 2" is connected by wire 26! to the wire 259 and is therefore connected to the lower end of the transformer secondary. From the foregoing wiring arrangement, it should be apparent that the three control resistances 233, 241 and 250, the balancing resistance 226, and the relay coils M6 and 2H in series, are connected in parallel. across the terminals of the secondary 253. flow of current will therefore take place through each of the resistances and through the relay coils. To the junction of relay coils 2l6 and 211 is connected 9. wire 262, this wire being connected to the control arms 23l, 239, 249, and to the balancing arm226 as shown, rheostats 263,264 and 265 being interposed between this wire 262 and the control arms 239, 249, and the balancing arm 225 respectively. By this arrangement it will be apparent that each of the control arms and the balancing arm divides its respective resistance into a first portion which is'in parallel with the relay coil 216 and a second portion which-is in parallel with the relay coil 2".

-Movement of any one of the control arms or the balancing arm across its respective resistance will therefore vary the resistance in parallel with each of the relay coils, and thereby vary the relative eneiigizations of said relay coils.

With the cont-rollers in the position shown, each control arm is engaging the midportion of its corresponding resistance and the proportioning motor I5 has therefore assumed an interdiate position in which the balancing arm 225 engages the center of the balancing resistance- 226, this resulting in the relay coils 216 and 211 being equally energized, thereby causing the switch arm 2l8' to be disengaged from the contor the dampers l2 and I3 are each in half-open position. If now should the space temperature increase, the control arm 231 of the controller 22l will be shifted to the, right,'this decreasing the portion of the control resistance233 which is in parallel with the relay coil 2H and increasing the portion of said resistance which is in parallel Reference character 251 indicates a step-down left across the balancing resistance 226.

- 268 to the other side of secondary 253; This energization of the motor field 213 will cause theoperating shaft of the motor to be rotated in a direction to open the face dampers 12 and to close the by-pass dampers '13. At the same time the balancing arm 225 will be shifted to the This will decrease the portion of said balancing resistance which is in parallelwith the relay coil 216 and increase the portion of. said resistance which is in parallel with the relay-coil 211, this causing an increase in current flow in the relay coil 211' and a decrease in current flow in relay coil 216, thereby tending to balance out the initial unbalancing efiect of the controller 221. When the shaft 208 has been rotated sufficiently to cause the balancing potentiometer to balance out the initial unbalancing action of the cntroller 22 I, the current flow in the relay coil 216 and 211 will become equalized, this resulting in the switch arm 218 disengaging the contact 219 thereby stopping the motor in this new position.

It will be apparent that the greater the initial unbalancing action is, the further the shaft 208 must rotate for causing the balancing potentiometer to balance out such unbalancing action. The rotation of the shaft 208 will therefore be in proportion to the movement of the control arm 231 on its control resistance. The movements of the face and by-pass dampers will to open the by-pass dampers 13. As in the case of increasing temperature, the movement of the dampers 12 and 13 upon falling temperature will be inproportion to the change in temperature.

The control arrangement just described will act to maintain the space temperature within the range of the controller 221 assuming of course that the capacity of the refrigeration system is sufiicient for all conditions. Thus, if the cooling load should increase, the space'temperature will increase and in response to such an increase in temperature the controller 221 .Wlll cause the face dampers to be opened further and the by-pass dampers to be moved towards closed position. This will result in an increasein air flow across the cooling coil, thereby increasing the cooling effect of the refrigeration system to offset the increase in refrigeration load.

It will be noted that the rheostat 265 is interposed between the balancing potentiometer and the junctionof the relay coils 216 and 211. The purpose of this rheostat is to desensitize the balancing potentiometer, thereby increasing the sensitivity of the controller 221. In other words, the rheostat 265 acts to limit the flow of current through the balancing arm 225 of the balancing potentiometer and thus decreases the effect of said balancing potentiometer upon the relative energizations of relay coils 216 and 211.

By thus desensitizing the balancing potentiometer relative to the control potentiometer of the controller 221, a relatively small movement of the control arm 231 on its control resistance 233 may be made to create an unbalancing action on the relay 215 such that a relatively large movement of the balancing potentiometer is required for rebalancing. Thus by properly adjusting th'e rheostat 265, the proportioning motor 15 may be made to shift the dampers from one extreme position to the other for a movement of the control arm 231 through but part of its operating range. In .other words, the rheostat 265 acts to make the operating range of the controller 221 less than its total range.

If the humidity within the space should increase, the control arm 239 will be shifted to the right across the control resistance 241, this having the efiect of decreasing the portion of said resistance which is in parallel with the relay coil 211 and increasing the portion of said resistance which is in parallel with the relay coil 216, .thus causing a decrease in current flow in coil 211 and an increase in current flow in coil 21 6, this causing the switch arm 218 to engage the contact 219, thereby energizing the motor field 213 to cause rotation of the operating shaft 208 in the direction to open the face dampers 12 and to close th by-pass dampers 13. The resulting movement of the balancing 'potentiom eter will tend to balance out the initial unbalancing efiect created by the controller 222, and when the rotation of the shaft 208 is such that the balancing potentiometer completely balances out said unbalancing effect, the switch arm 210 will disengage contact 219, thereby stopping the motor and dampers in this new position. Upon a decrease in humidity it will be apparent that the opposite action will take place. In other words, the operating shaft of the motor will be rotated in the opposite direction an amount corresponding to the decrease in humidity. The humidity controller 222 will therefore act to cause the proportioning motor, 15 to position the dampers'for increasing the air flow across the cooling coil 9 upon an increase in humidity and to cause opposite movement upon a decrease in humidity." 7

Assuming now that the space temperature remains constant but the relative humidity increases, the controller 222 in the manner just described will cause movement of the face damper 12 towards open position and the by-pass damper 13 towards closed position. This will result in an increase in cooling effect of the cooling coil 9 which ultimately will result in the space temperature beginning to fall. As the space temperature falls, the controller 221 will cause the proportioning motor 15 graduallyto, close the face dampers 12 and to open the bypass dampers 13, thereby decreasing the cooling effect of the system, and when the space temperature falls sufficiently that the decrease in cooling effect caused thereby is sufficient to prevent further fall in temperature, the space temperature will be held constant at this new value. Hence upon an increase in humidity, the controller 221 will be caused to maintain a lower value of space temperature. In a similar manner, it will be apparent that upon \a decrease in humidity, the controller 226 will be caused to maimain an increased value of temperature. The humidity controller 222 therefore acts as a compensator or adjustor forthe return air temperature controller 221, said humidity contemperature controller upon variation in humidity. It will be observed that the nheostat 263 is connected between the control arm 23!! of said humidity controller and the junction of the relay coils 2l6 and U1. The purpose of this rheostat is to vary the effect of the humidity controller upon the control .point of the temperature controller. By properly adjusting this rheostat, the humidity controller may be made to vary the control point of the temperature controller upon a change in relative humidity an amount which just compensates for the change in effective or comfort temperature caused by such change in relative humidity. The temperature controller 22! and the humidity controller 222 therefore cooperate to maintain a constant effective temperature within the space, the dry bulb temperature being raised or loweredupon changes in relative humidity to accomplish this result.

Assuming now that the space temperature and relative humidity remain constant, if the outside temperature should increase, the control arm 249 of .the controller 223 will be shifted to the right across the control resistance 250, this acting to decrease the portion of said resistance which is in parallel with the relay coil 2H5, and to increase the portion of said resistance which is in parallel with the relay coil 2", this causing an increase in current flow in relay coil 2 l1 and a decrease in current flow in relay coil 2 l6, which results in the switch arm 2l8 engagingthe contact 220 for rotation of the operating shaft 208 in a direction to close the face dampers l2 and to openthe by-pass dampers I3. Simultaneously the balancing arm 225 of'the balancing portentiometer will be shifted to the right across the resistance 226, this decreasing the portion of said resistance which is in parallel with relay coil 2" and increasing the portion of said resistance which is in parallel with relay coil 216, thereby tending to balance out the initial unbalancing action of the controller 223. the movement of the dampers and the balancing arm 225 is sufficient to cause rebalancing 'of the relay, the switch arm 2|8 will disengage contact 220 and the proportioning motor will When stop in this new position.- It should thus be apparent that upon an increase in outside temperature, the controller 223 will act to cause the air flow across the cooling coil 9 to be decreased and the air flow by-passed therearound to be Assuming now that the outside temperature rises, the dampers l2 and I3 will be positioned in the manner just described to cause a decrease in flow of air across the coolingcoil thereby decreasing the cooling eflect of said'coil. This decrease in cooling eifect will eventually result in rising of temperature within the conditioned space, this rise in temperature acting upon the controller MI in a manner to cause opening of the face dampers l2 and closing of the by-pass dampers l3 to increase gradually the cooling eifect. When the rise in space temperature is such that the resulting increase in cooling effect caused by the controller 22l is suflicient to pre vent further rise in temperature, the space temperature will be held constant at this new value.

. to cause the return, air temperature controller to maintain a higher value of temperature within the conditioned space. It will be apparent that upon falling outdoor temperature, the opposite action will take place, namely, the controller 22! will be caused to maintain a lower value of temperature within the conditioned space. The purpose of this controller is to provide an adjustment of indoor temperature with outdoor temperature in accordance with standard air conditioning practice. By adjusting the rheostat 264 the effect of the controller 223 on the control point of the indoor controller 22l may be variedv as desired.

In this embodiment of the invention, the use of a reheater in many cases will be unnecessary for the by-pass arrangementwill usually provide sufiicient reheat for the air discharged from the cooling coil. In certain installations, however, the continuous operation of the cooling coil for maintaining a constant dew-point of the discharged air may at times cause overcooling of the conditioned space, and a reheater may therefore be desirable. If desired, the reheater if employed may be sequentially controlled with the face and by-pass dampers as in Fig. 1. In Fig. 2, however, instead of illustrating modulating control of the reheater as in Fig. 1, we have shown in this figure a two-position type of control. This reheat controller comprises a. cam 210 mounted upon the operating shaft 208 of the proportioning motor l5, this cam cooperating with a pivoted switch carrier 21! carrying a mercury switch 212. The cam 210 is arranged upon the proportioning motor shaft 208 in such manner that the switch is tilted to closed position only when the operating shaft is moved to its extreme limit of rotation, in which the face dampers I2 are moved to their minimum positions and the by-pass dampers l3 are opened. For other positions of the face and by-pass dampers, the cam 210 will cause tilting of the mercury switch 212 to open position. The pump 42 in this instance, instead of being driven by the internal combustion engine is driven by an electric motor 213, the operation of this motor being controlled by the mercury switch 212. From this arrangement, it will be apparent that as the space temperature falls, the face dampers l2 will be closed gradually and the by-pass dampers l3 will be opened gradually. Upon continued fall in temperature, the face dampers l2 will eventually assume a maximum closed position and the by-pass dampers will assume a wide' open position, at which time the cam 210 will be rotated just sufficiently to cause making of mercury switch 212 which results in operation of the pump motor 213, causing a circulation of heated water from the storage tank I25 through thereheater l6 and back to the tank. When the pump is out of operation, circulation of water from the tank I25 through the reheater I6 is prevented by moved towards closed position in a manner to v increase the cooling effect of the system sufficiently to prevent further increase in effective temperature. The resulting increase in air flow over the cooling coil 9 will increase the amount of refrigerant evaporated within said cooling coil, and hence will cause the suction pressure to increase., This increase in suction pressure will effect the suction pressure controller 200 in a manner to cause the proportioning motor 46 to open the throttle valve farther. This will increase the flow of fuel to the internal combustion engine 25, thereby increasing its speed which in turn results in increased output of the compressor II. In this manner the compressor output will be increased upon an increase in effective temperature within the space. Upon falling effective temperature, it will be apparent that the opposite action will take place, namely, that the face and by-pass dampers will be positioned to restrict the flow of air across the cooling coil 9. This will result in less refrigerant being evaporated within said cooling coil, which in turn will cause lowering of the suction pressure. In response to this decrease in suction pressure, the pressure controller 200 will cause'operation of the proportioning motor 46 in a direction to move the throttle valve 45 towards closed position.

This will result in decreasing the fuel supply to the engine, thereby decreasing the operation of the compressor in a manner to prevent further decrease in suction pressure. Upon falling temperature, therefore, the system will act to decrease the flow of air over the cooling coil 9 and this will result in the suction pressure controller causing slowing down of the engine speed. The control system which we have disclosed will therefore act to vary the engine speed in accord ance with the cooling load.

Upon continued fall in cooling load the space temperature will decrease further, this eventually resulting in partially closing of the face dampers I2 and opening of theby-pass dampers l3, thereby reducing the air flow across the cooling coil 9 to a minimum. At this time the mercury switch 212 will be tilted to closed position by the cam 210 which causes operation of the pump 42 for supplying heated fluid to the reheater IS, thereby preventing any further fall in temperature.

It will be noted that in this embodiment the proportioning motor 46 which positions the throttle valve 45 actuates also a mercury switch 215, this mercury switch corresponding to the mercury switch I02 of Figure 1. Thus whenever the throttle valve 45 is closed to such an extent as to indicate that the engine is operating at too low a speed for satisfactory operation, the mercury switch 215 will be tilted to open, position, this causing stopping of the engine. It will also be apparent that as the suction pressure rises and causes the proportioning motor 46 to open the throttle valve 45 to such an extent as to demand operation of the engine at a satisfactory speed, the mercury switch 215 will be tilted to closed position, this energizing the ignition circuit for the engine and also energizing the starting apparatus therefor, thereby placing the engine in operation. By this arrangement, therefore, the speed ofthe engine will be varied in accordance with the refrigeration load, and when the refrigeration load falls to such an extent as to require operation of the engine at too low a speed the engine will be placed out of operation.

While we have shown and described only two forms which our invention may take, it is obvious that many other changes which are within the scope of our invention will be apparent to those skilled in the art. We therefore desire to be limited only by the scope of the appended claims a said internal combustion engine, motor means for adjusting said control means to vary said compressor output, humidity responsive means for controlling said motor means in a manner to cause the engine speed to be increased progressively with increasing humidity, and means re sponsive to temperature for also controlling said motor means, said temperature responsive means being arranged to cause increase in speed of said enginewhen the temperature exceeds a predetermined value.

2. In an air conditioning system, in combination, a cooling device through which air in a space is adapted to be passed for conditioning thereof, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, an internal combustion engine for driving said compressor, control means for varying the output of said internal combustion engine, a controller for stopping and starting said internal combustion engine, motor means for adjusting said control means and for positioning said controller, said controller being positioned by said motor means to stop said internal combustion engine when the said control means is adjusted to cause an engine output below a predetermined minimum and to cause starting of said engine when said control means is adjusted to cause an engine output above said predetermined minimum, and humidity responsive means 'for controlling said motor means, said humidity responsive means and said motor means being arranged to cause the output of said engine to be progressively increased with increasing values of humidity.

3. In an air conditioning system, in combination, a cooling device through which air in a space is adapted to be passed for conditioning thereof, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, an internal combustion engine for driving said compressor, control means for varying the output of said internal combustion engine, motor means for adjusting said control means to vary said output, humidity responsive means for control ling said motormeans in a manner to cause the engine, output to be increased progressively with increasing humidity, and means for starting said engine when said engine. output controlling means is adjusted to demand an engine output above a predetermined minimum value.

4. In an air conditioning system, in combination, a cooling device through which air in a space is adapted to be passed for conditioning thereof, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, an internal combustion engine for driving said compressor, control means for varying the output of said internal combustion engine, motor means for adjusting said control means to vary said output, humidity responsive means for controlling said motor means in a manner to cause the engine'output to be increased progressively with increasing humidity, and means for stopping said engine when said engine output controlling means is adjusted to demand an engine output below a'predetermine'd minimum value.

5. In an air conditioning system, in combination, a cooling device through which air passingto a space is adapted to be passed for conditioning thereof, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, an internal combustion engine for driving said compressor, control means for varying the output of said internal combustion engine, motor means for adjusting said control means to vary-said output, a humidity controller influenced by the space relative humidity, and means for rendering said humidity controller effective to control said motor means and hence said engine control 'means, said last recited means comprising means controlled by said humidity controller for varying the flow of air through said cooling device, and means actuated in response to resulting changes in condition of said cooling device con-' nected to said motor means in a manner tending to maintain said condition at a predetermined value.

6. In an air conditioning system, in combination, a cooling device through which air passing to a space is adapted to be passed for conditioning thereof, flow control means for controlling the flow of air through said cooling device, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, an internal combustion engine for driving said compressor, control means for varying the speed of said internal combustion engine, motor-means for adjusting saidcontrol means to vary said speed, space humidity responsive means for controlling said motor means in a manner to cause the engine speed to be increased progressively with increasing humidity,

and space temperature responsive means for conthe flow-of air through said cooling device, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, an internal combustion engine for driving said compressor, control means for varying the output of said internal combustion engine, motor means for adjusting said con- ,trol means to vary said output, space humidity responsive means for controlling said motormeans in a manner to cause the engine output to be increased progressively with increasing hu-, midity, space temperature responsive means for also controlling said motor means, in a manner to increase the engine output independently of said humidity responsive meanswhen space temperature rises to a predetermined high value. and space temperature responsive means for controlling said flow control means in a manner to decrease the flow of air through said cooling device upon decrease in temperature, while increasing said air flowupon increase in temperature.

8. In an air conditioning system, in combination, a cooling device through which air passing to a space is adapted to be passed for conditioning thereof, flow control means for controlling the flow of air through said cooling device, a first motor means for actuating said flow control means, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, an internal combustion engine for driving said compressor, control means for varying the speed of said internal combustion engine, a second. motor means for adjusting said control means to thereby vary the speed of said engine, space temperature responsive means for controlling one of said motor means, and space humidity responsive means for controlling the other of said motor means.

9. In an air conditioning system, in combination, a cooling device through which air passing to a space is adapted to be passed for conditioning thereof, flow control means for controlling the flow of air through said cooling device, motor means for actuating said flow control means, means including space temperature and relative humidity responsive means and outside temperature responsive means for conjointly controlling said flow control means, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system includ ing a compressor, control means for varying the output of said internal combustion engine, motor means for adjusting said control means to vary said output, and means responsive to the condition of said cooling device for controlling said last mentioned motor means in-a manner tending to maintain said condition constant.

10. In an air conditioning system, in combination, a cooling device through which air passing to a space is adapted to be passed for conditioning thereof, flow control means for controlling the flow of air through said coolingdevice, motor means for actuating said flow control means, thermostatic means influenced by outside temperature for controlling said motor means to thereby vary the action of said flow control means in accordance with variations in outside temperature', means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, control means for varying the output of said internal combustion engine, motor means for adjusting said control means to vary said output. and means responsive to the condition of said cooling device for controlling said last mentioned means in a manner tending to maintain said condition constant.

11. In an air conditioning system. in combina-' tion, a cooling device through which air passing to a space is adapted to be passed for conditioning thereof, flow control means for-controlling the flow of air through said cooling device, motor means for actuating said flow control means, means including space temperature responsive means for controlling said motor means to thereby vary the action of said flow control means in accordance with variations in space temperature, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, control means for varying the output of said internal combustion engine, motor means for adjusting said control means to vary said output, and means responsive trolling said last mentioned motor means in a -manner tending to maintain said condition constant.

12. In an air conditioning system, in combifor said engine, automatic starting mechanism for said engine, said automatic starting mechanism having a control switch, a motor for actuating said speed controller and said control switch and means including a device responsive to the relative humidity in said space for determining the position assumed by said motor.

'13. In an air conditioning system, in combination, a cooling device through which air in a space is adapted to be passed for a conditioning action, means for supplying cooling fluid to said cooling device comprisinga mechanical refrigeration system including a compressor, a variable speed internal combustion engine for. driving said compressor at varying speeds, a speed controller for said engine, automatic starting mechanism for said engine, said automatic starting mechanism having a control switch, a motor for actuating said speed controller and said control switch, a controller for said motor, said controller being connected to said motor, and means responding to the relative humidity in said space for actuating said controller.

14. In an air conditioning system, in combina tion, a cooling device through whichair in a space is adapted to be passed for a conditioning action, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system. including a compressor, a variable speed internal combustion engine for driving said compressor at varying speeds, a speed controller for said engine, automatic starting mechanism for said engine, said automatic starting mechanism having a control 1 switch, a motor for actuating said speed controller and said control switch and means for changing the position assumed by said motor in 7 response to changes in relative humidity, said last named means comprising a damper positioned by a humidity responsive device for controlling the load applied to said cooling, device and a device responsive to the load applied to said cooling device for controlling said motor.

15. In an air conditioning system, in combination, a cooling device through which air in a space is adapted to be passed for a conditioning action, a by-pass for flow of air around said cooling device, damper means for controlling the proportions of air passed through said cooling device and through said by-pass, damper motor means for positioning said damper means, thermostatic means responsive to the temperature in said space for controlling said damper motor means, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, a variable speed internal combustion engine for driving said compressor at varying speeds, a speed controller for said engine, automatic starting mechanism for said engine, said automatic starting mechanism having a control switch, a motor for actuating asid speed controller and said control switch in a manner to start said engine and increase the speed of said engine as said motor moves from one position to another, and a controller for controlling the position assumed by said motor.

16. In an air conditioning system, in combination, a cooling device through which air in a space is adapted to be passed fora conditioning action, a by-pass for flow of air around said cooling device, damper means for controlling the proportions of air passed through said cooling device and through said by-pass, damper motor means for positioning said damper'means, thermostatic means responsive to the temperature in said space for controlling said damper motor means, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, a variable speed internal combustion enginefor driving said compressor at varying speeds, a speed con troller for said engine, automatic starting mechanism for said engine, said automatic starting mechanism having a control switch, a motor for actuating said speed controller and said control switch in a manner to start said engine and increase the speed of said engine as said motor 'moves from one position to another, and means responding to relative humidity and connected to said motor for controlling the position assumed by said motor.

17. In an air conditioning system, in combination, a cooling device through which air in a space is adapted to be passed for a conditioning action, a by-pass for flow of air around said cooling device, damper means for controlling the proportions of air passed through said cooling device and through said by-pass, damper motor means for positioning said damper means, thermostatic means responsive to the temperature in said space for controlling said damper motor means, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, a variable speed internal combustion engine for driving said compressor at varying speeds, a speed controller for said engine, automatic starting mechanism for said engine, said automatic starting mechanism having a control switch, a motor for actuating said speed controller and said control switch in a manner to start .said engine and increase the speed of said engine as said motor moves from one position to another. and means responding to a condition which is a measure of the load applied to said cooling device by said damper means for controlling the position assumed by said motor.

18. In an air conditioning system. in combination, a cooling device through which air in a space is adapted to be passed for a conditioning action, means for supplying cooling'fiuid to said cooling device comprising a mechanical refriger ation system including a compressor, a variable speed internal combustion engine for driving said compressor at varying speeds, a speed controller for said engine, automatic starting mechanism for said engine, said automatic starting mechanism having a control switch, a motor for actuating said speed controller, means responsive to the relative humidity in the space for controllin said motor to thereby vary the speed of said- ,bination, a cooling device through which air'in a space is ada'pted'to be passed for a conditioning action, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, a variable speed internal combustion engine for driving said compressor at varying speeds, a speed controller for saidengine, automatic starting mechanism for said engine, said automatic starting mechanism having a control switch, a motor for actuating said speed controller, means responsive to the relative humidity in the space for controlling said motor to thereby vary the speed of said engine in accordance with space relative humidity, and means'for closing said control switch irrespective of the value of relative humidity in said space when the temperature rises to a predetermined value for thereby placing the engine into operation.

20. In an air conditioning system, in combination, a cooling device through which air in a space is adapted to be passed for a conditioning action, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, a variable speed internal combustion engine for driving said compressor at varying speeds, a speed controller for said engine, a motor for actuating said speed controller, said motor having control line means, a thermostat connected into said control line means for controlling said motor, and a humidity controller also connected into said control line means for causing the motor to increase the engine speed upon increase in humidity.

21; In an air conditioning system, in combination, a cooling device through which air in a space is adapted to be passed for a conditioning action, means for supplying cooling fluid to said trol line means for causing the motor to increase the engine speed upon increase in humidity and for starting said engine when the humidity rises above a predetermined value. .v

22. In an air conditioning system, in combination, a coolingv device through which air in a space is adapted to be passed for a conditioning action, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, a variable speed internal combustion engine for driving said compressorat varying speeds, a speed controller for said engine, a motor for actuating said speed controller, said motor having control line means, a thermostat connected into said control line means for controlling said motor, a humidity controller also connected into said control line means for causing the motor to increase the engine speed upon increase in humidity and for stopping said engine when the relative humidity in said space falls to a. predetermined value.

23. In an air conditioning system, in combination, a cooling device through which air in a. space is adapted to be passed for a conditioning action, means for supplying cooling fluid to said cooling device comprising a mechanical refrigeration system including a compressor, a variable speed internal combustion engine for driving said compressor at varying speeds, a speed controller for said engine, automatic starting mechanism for said engine, said automatic starting mechanism having a control switch, electrical means for actuating said starting switch and said speed controller, control means for controlling said electricalmeans in a manner to start the engine and vary its speed, and other control means for controlling said electrical means to cause closing of said control switch irrespective of the operation of said first control means for thereby placing said engine into operation, one of said control means responding to the temperature of said space and the other of said control means responding to the relative humidity of the air in said space.

LEO B. MILLER.

WILLIAM L. McGRATI-I.

JOHN E. HAINES. 

